Chemischer InformationsdienstVolume 15, Issue 13 Physical Inorganic Chemistry ChemInform Abstract: THE ELECTRICAL CONDUCTIVITY AND MAGNETIC SUSCEPTIBILITY OF GERMANIUM(II) MONOSELENIDE IN THE SOLID AND LIQUID STATES L. ROSS, L. ROSSSearch for more papers by this authorM. BOURGON, M. BOURGONSearch for more papers by this authorJ. J. HECHLER, J. J. HECHLERSearch for more papers by this author L. ROSS, L. ROSSSearch for more papers by this authorM. BOURGON, M. BOURGONSearch for more papers by this authorJ. J. HECHLER, J. J. HECHLERSearch for more papers by this author First published: March 27, 1984 https://doi.org/10.1002/chin.198413013Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References L. ROSS, M. BOURGON, J. J. HECHLER, THE ELECTRICAL CONDUCTIVITY AND MAGNETIC SUSCEPTIBILITY OF GERMANIUM(II) MONOSELENIDE IN THE SOLID AND LIQUID STATES, Thermochim. Acta, 1983, 71, 323. DOI: 10.1016/0040-6031(83)80065-3; Volume15, Issue13March 27, 1984 ReferencesRelatedInformation

The specific conductivity of germanium(II) monoselenide has been measured, under equilibrium pressure, from room temperature to 802°C. Interpretation of the results leads to the conclusion that the intrinsic conductivity is observed in the solid in the upper temperature range: the calculated energy gap is E0g = 1.222 ± 0.027 eV which coincides with the value of the optical gap. In liquid GeSe the calculated energy gap is 1.504 ± 0.016 eV. This increase of the energy gap in liquid GeSe is due, presumably, to the strengthening of the intralayer bonds of the structure. Electrical conductivity and magnetic susceptibility measurements confirm the existence of a polymorphic transformation in GeSe at 656°C.

The Ge–Se phase diagram was determined in the composition range 0–66.67 at. % Se by the method of differential thermal analysis. The diagram differs totally from the one reported by Liu etal. (1) but is in good agreement with the diagram recently reported by Karbanov etal. (13). In its broad features the Ge–Se phase diagram is quite similar to the diagrams of the Ge–S, Sn–S, and Sn–Se systems.

Germanium(II) sulfide has been studied by the technique of differential thermal analysis. The results show that the reported Ge—S phase diagram may be in error: no evidence has been found for a solid-state transition at 590 °C and GeS appears to undergo peritectic disproportionation at approximately 650 °C.

The specific conductivity of germanium(II) sulfide has been measured, under an inert atmosphere, from room temperature to the boiling point (750 °C). Interpretation of the results indicates that the intrinsic conductivity is observed in the solid in the upper temperature range: the calculated energy gap is 1.58 eV which coincides with the value of the optical gap for indirect transition. The calculated energy gap of liquid GeS is 2.3 eV and it is shown that the increase in the gap occurs on melting and is not due to a transformation in the solid.

The electrical conductivity of germanium(II) sulfide in the liquid state has been measured with a capillary-type cell. Both a-c. and d-c. methods were used. The conductivity of liquid GeS increases regularly with tempersature from 1.33 Ω−1 cm−1 at 664 °C to 2.52 Ω−1 cm−1 at 705 °C. The experimental facts lead to the conclusion that GeS remains a semiconductor in the liquid state with a conduction band situated at 2.5 eV above the valence band.The energy gaps of GeS, SnS, and PbS in the solid state are compared with those of the corresponding liquids. It is concluded that these sulfides, in the liquid state, have structures very similar to that of the solids. Liquid PbS has a structure somewhat similar to that of metals. In the case of SnS and GeS, heating and melting are accompanied by a gradual loosening of the double layers which constitute the crystals. Accumulated evidence indicates that the molecular character of SnS and GeS is increased on going from the solid to the liquid state.

The electrical conductivity "σ" of tin (II) sulphide in the liquid state has been measured using a capillary type cell. Both a-c. and d-c. methods were used. The conductivity of SnS increases regularly with temperature, from approximately 24 ohm−1 cm−1 at 895 °C to 31.2 ohm−1 cm−1 at 930 °C. The similarity of results obtained with both a-c. and d-c. methods, the positive temperature coefficient of conductivity, the high value of the conductivity and the absence of electrolysis effects when passing heavy currents in the melt lead to the conclusion that SnS remains a semiconductor in the liquid state. The value of the energy gap has been calculated to be 1.9 ev for the liquid as compared to the value 1.2 ev for the solid. Conductivity measurements have been limited to the temperature of approximately 935 °C because of the decomposition of SnS at higher temperatures.

The conductivity of liquid copper sulfide has been measured as a function of the mole fraction of sulfur in the melt at three temperatures: 1170°, 1250°, and 1300°C. The results show that a) the conductivity of copper-rich Cu2S is independent of the sulfur pressure in the furnace, and b) the conductivity of sulfur-rich copper sulfide increases rapidly with sulfur pressure. Assuming that the band theory is applicable to liquids leads to the conclusion that copper-rich copper sulfide is an intrinsic semiconductor, in which case electrons act as carriers. The activation energy for conduction in this case has been calculated to be 0.7 ev. On the other hand, sulfur-rich copper sulfide behaves as a p-type semiconductor, positive holes being responsible for conduction.